Micromass Quattro Ultima, User Manual

Page: 108 / 227

Calibration Parameters
These are accessed from
Edit
,
Calibration Parameters...
.
The Peak Match parameters determine the limits within which the acquired data
must lie for the software to recognise the calibration masses and result in a successful
calibration. The default values are shown.
Increasing the
Peak window and
Initial error
gives a
greater chance of incorrect
peak matching. All peaks in
the acquired spectrum
below the
Intensity threshold value
(measured as a percentage
of the most intense peak in
the spectrum) are not used
in the calibration procedure.
The
Polynomial order
of
the curve has values from 1
to 5 as the available
options:
A polynomial order of
1 should not be used.
An order of 2 is suitable for wide mass ranges at the high end of the mass scale,
and for calibrating with widely spaced reference peaks. Sodium iodide in
particular has widely spaced peaks (150 amu apart), and horse heart myoglobin
is used to calibrate higher up the mass scale, so this is the recommended
polynomial order for these calibrations.
An order of 3 fits a cubic curve to the calibration.
A fourth order is used for calibrations which include the lower end of the mass
scale, with closely spaced reference peaks. This is suitable for calibrations with
PEG which extend below 300 amu..
A fifth order fit rarely has any benefit over a fourth order fit.
Mass Calibration
Page 108
Quattro Ultima
User's Guide